文章建立了自动电位滴定法测定有机肥料中有机质的方法。确定了滴定的加液步长为0.05 mL,等当点识别标准为100 mV,在此条件下可获得圆滑的滴定曲线和准确的滴定结果。进行不同含量的有机肥标准样品的精密度及准确度考察,结果显示,相对标准偏差在0.46%~0.81%之间,相对误差在−1.29%~3.3%之间,且测定结果均在标准值的不确定度范围之内。通过与经典滴定法的比对试验并对试验结果进行t检验及F检验,各试验组的t值均小于t (0.05, 2n-2)值,F值小于对应的临界值,即方法之间的准确度及精密度不存在显著性差异。建立的方法具有操作简便、准确可靠、重复性好、效率高等优点,适用于有机肥料中有机质含量的测定。A method for determining organic matter in organic fertilizers using automatic potentiometric titration has been established. The addition step size for titration has been determined to be 0.05 mL, and the identification standard for equivalent points is 100 mV. Under these conditions, a smooth titration curve and accurate titration results can be obtained. The precision and accuracy of organic fertilizer standard samples with different contents were investigated, and the results showed that the relative standard deviation was from 0.46% to 0.81%, and the relative error was from 0.3% to 3.3%. The measurement results were all within the uncertainty range of the standard values. Through the t-tests and F-tests, it was found that the t-values of each experimental group were less than the t (0.05, 2n-2) value, and the F-values were also less than the corresponding critical values, indicating that there was no significant difference in accuracy and precision between the methods. The method has the advantages of simple operation, accuracy and reliability, good repeatability, and high efficiency, and is suitable for the determination of organic matter content in organic fertilizers.
